Myokymia predominantly affects which muscle?

Myokymia predominantly affects which muscle?

• A. Corrugator
• B. Orbicularis oculi
• C. Levator palpebrae superioris
• D. Procerus

Answer: (B)

Myokymia is a spontaneous, fine, ripple-like contraction of a muscle. In the eyelid, this twitching most commonly involves the orbicularis oculi, the circular muscle that closes the eyelids. Because the orbicularis oculi controls lid closure and is richly innervated and prone to localized motor-unit hyperexcitability, small, repetitive discharges produce the characteristic eyelid flutter. The other muscles listed have different roles (the levator opens the lid; corrugator and procerus are involved in brow and nasal skin movements) and are not the usual site of this twitching. So the orbicularis oculi is the best match for myokymia.

Myokymia is a spontaneous, fine, ripple-like contraction of a muscle. In the eyelid, this twitching most commonly involves the orbicularis oculi, the circular muscle that closes the eyelids. Because the orbicularis oculi controls lid closure and is richly innervated and prone to localized motor-unit hyperexcitability, small, repetitive discharges produce the characteristic eyelid flutter. The other muscles listed have different roles (the levator opens the lid; corrugator and procerus are involved in brow and nasal skin movements) and are not the usual site of this twitching. So the orbicularis oculi is the best match for myokymia.